This invention relates generally to planetary gears, and, more particularly, to a planetary gear comprising a sun wheel mounted on a center spindle, at least one planet wheel mounted on a rotatable planet carrier, and an annulus surrounding the wheels, the planet wheel being in drive connection on the one hand to the sun wheel and on the other to the annulus, at least one of these elements being connected to a stationary part.
Such planetary (or epicyclic) gears generally comprise at least three elements rotatable about a common central axis, namely, e.g., a central sun wheel rotatably mounted on a gear casing by means of a spindle, at least one planet wheel rotatably mounted via at least one further spindle on a planet carrier, and a rotatably arranged outer annulus surrounding the sun wheel and planet wheel. Such planetary gears are mostly configured as gear wheel assemblies wherein the planet wheel meshes with both the interior sun wheel and with the outer annulus. In this arrangement the planet wheel, also termed epicyclic wheel, is rotatable not only about its own axis (epicyclic axis) but also about another axis, namely the central axis of the sun wheel. The planet carrier is also termed a web. When this revolves about the central axis, at least one of the three gear wheels may be stationary, namely the sun wheel or annulus, or two or also three of the gear wheels may revolve.
Normally, one of the three elements (sun wheel, planet wheel with planet carrier, annulus) is connected to an input drive and a second of these parts is connected to an output drive. The third part required, to handle the counter-torque, is connected to a stationary frame or casing either fixedly or releasably via a coupling or brake. As a result of this configuration, the gearing effect is constant, providing power transmission, regardless of the driving direction.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.